Prefired transmit-receive box system



April 29, 1952 B. B. CORK PREFIRED TRANSMIT-RECEIVE BOX SYSTEM 2SHEETS-SHEET l Filed May 9, 1945 INVEN TOR. BRUCE B. CORK ATTRNEY April29, 1952 B, B, gORK PREFIRED TRANSMIT-RECEIVE BOX SYSTEM 2 SHEETS-SHEET2 Filed May 9, 1945 FIG. 3

FIG. 2

F lG. 4

INVENTOR. BRUCE B. CORK ATTORNEY Patented Apr. 29, 1952 ommen Simms-foit-ie:

PREFIRE'D This .invention relatesfitiaipresredsilk .fggi :1 for use in atransmit-receive (hi-gh. frequent'-yvv .radio fe echo systemas.afprotectsieiswtching;devicei. and

. more.; particularlygto an arrangementtof and In;ordenftoasimplygcertain; aspects ,offxoperae tionzotzmannzradiogecho.syter.ns,-. itv is expedient tot-:use,thesamefantenna.:'ioritransmittingand receivingii. A swgitchingieffeotis Lrequire'd to conf. t neet.andidseonneetthe transmitter and. receiveralternately; to. 'this antenna, because if bothv wereconneetetiyall;gthetime f the-receiver would`vbe damagedfandblockedibynithe (transmitted. pulse of h igligfrequenoy energy,- 'and.also incidentally,t the output epowento-.the antenna would .bedecreased. Onfzthefothemhanompart i of-the ,energy A of refoei-.ved-.echosignalsl would be diverted. tothe transmitten thus:reducing-fthe, -.-arno un t going .tothe recrsiter-t presented.by4most: magnetron. .transmitters bef tween the transmitting and the:quiescent state, the :diversion of received signals can be preventedwithout yd i'sronnection...bi/z. proper .lengthiof connecting-,lines017;.wave fg'uides between the transmitterfami-theantenna--TviunQtionTor pro.- tect tnecnsitive Y.reztver., from.. the. very large asfnearly;perfect,isolation..oi.the receiver as', posf sible ,during-the' lpulse..i., It .is necesary that ,the

Seton@ .:from:y l@tlufaetart :,or....thef.pu1se and provide... aegpod.shorticrcuit..ot-.thefreceiver during the..

pillte.

Commonlyvusexi forthieliort .circuitlng eti/itiri,y

isy a:gasidischargeaross .a gap which. isshunted aorosethe resettenline. so Ltritt .when the ...pulse and .reflect .high impedance. backto. .the Taunt 0i :voltage then..each1ng thereceiyer.depends'iontransformer ,takes the` or :inthemicrof-wave .region. of.. the spectruma cylindrical resonant....ca..vitiy.` This acts as.: an`

l l hesite. maximum. electric eld. and .maximumwoltagaat the centenwhere Agmuch; sma11ei:input ',will j.

auto-,transformer .and

the.; gen .,isiplacecl..

I 4o. oeeuretheeap .,.willire .andvshort circuit .the line.

2.? therrcause ring @time Since; it requires-ia... higher potentialto-.breakf down :anatre :.the. eaptthan-to.maintain-the nrc. during theremainder of the high frequencypinetaA anything:- rwhich.; .reduces .1,the. necessary breakdown.-potentieleproydesian. extra deereepffprwateithe reeionofztheeap- A. further-expedient.:

Itas. one.; object iof.-.fth.s.,.ni/entior1to construct ia..flspark.zgapxhayng addednauxiliary. electrodes.- so energized as topre-re the gap and y1nini1pizethefvaiueof .fthe .high .frequency,retentit-l .zw-high 'll rai/terse,` the gap.:

`itis..another,.object-ot.thstnventon to .Succo struct andarraneeftheizauxliary .elect-.rode

ajoute .useim connection '.wthga; Spark. gan-:atl tofreduceiorAe1iiriginate sputtering ,.offmetal par.-

ticles-fonto, thefglassfof. ,the-.ftubefin-:the :regioni Ofi thel:eap:..=.

It; is .-.another eobiect :0f- -this .intention ftofoir structa;transmitereceiveradio :echo systemV hav--` ing -aprefred-Lorfpref-pulsed .spark 4gap as. a .provtective. switchggtofenable. thenise-of. ionemantenna.

both-'for :transmitting 1 and for :freoeiving .'iwithl.. a maximum offprotection .to :the .receiver during-.the highrfrequencytransmi-.tted\;pu1s.e...;A

Other:.-objects andlafeaturesnwill be .revealed-i`byeoonsiderationcfofftthe ,-1foll'owing-f.:detailedv deff.

seriptionvtakeni with? the rvaccoinp anying drawingsl the f*iigiuesnof.:A whichi represent atypical `erribo die-lments'and'areinotto be construed as delningr limi-ting the :scope of theinvention.L

l is -a -1persp.ective'viewf of -one :formofftlie -i invention.

Fig 2 liseawsecticnn-Ktaken-on the line IIJ-Urol. Figg-lshowi-ngawesonant cavity with' fa sparkiga'p betweentwotn'iai-n'radiofrequency electrodes:

. and v'auxilijerw-eletrodes zrarranged l' in: :5 accordanceWithi-'thefteaohingfof ithlsninventions Fig, 3 'tis-aeliialffsectional1vView:correspondingto dFiere 2 *of anotherfarrangenient of-waHgapQ-arlf'to flfjie:. j-.Zrsiti-owing'arrrixngirovexiNJ arrangement fo''gapi-andesincefthefout; L put-:to'itherreceiverismroportonal. @thetrut-f Fig. 6 is a diagram of a system incorporating the principles ofthis invention.

Fig. l, shows in perspective, and Fig. 2 in section, a typicalembodiment; of the principle of this invention and shows a cylindricalconducting member I enclosing a resonant cavity IU with a coaxial linell having a center conductor 3 pro- `iecting into the cavity and turningback in a vertical loop i 2 to terminate in the wall of the member I,thus completing the circuit With the outer conductor 4. Another coaxialline I 4, not shown in Fig. 1, having a center conductor I5 is alsocoupled by another loop I2 to the cavity I0 at a point diametricallyopposite the one shown.

Inserted axially through the cavity I0 at the center is a glass tube 6secured within supporting member 5. Sealed leads 1 and 8 are forconnection to a source of potential difference, while sealed lead 9 isfor connection to a source of periodically produced relatively highpotential. As shown particularly in Fig. 2, the outer conductors of thecoaxial lines ll and I4 as well as the loops I2 of the center conductors3 and I5 thereof are conductively attached to the Wall of member I.

' These coaxial lines 4 and Ul are for connecting the cavity Ill to areceiver, and to the T-junction of a high frequency transmitter and anantenna. Echo signals from the antenna pass into the cavity I0 throughone coaxial line and out of the cavity I0 through the other coaxial lineto the receiver as diagrammatically shown in Fig. 6 to be describedhereafter. This method of coupling is suggestive only and other methodsof coupling the cavity I0 are available such as by slits opening thecavity I 0 into wave guides to and from the cavity.

A narrow gap I6 is formed between two hollow open-ended conicalprojections I1 and I8 through which the tube G extends, whichprojections constitute the main radio frequency gap electrodes. Metaltubes I9 and 20 are arranged Within and concentric with the conicalprojections I1 and I8 respectively and with the latter are secured' toannular caps 2i and 22. There are produced thereby radio-frequency chokecavities 23 and 24, which are provided in order to prevent the highfrequency energy from leaking olf into leads 1 andv 8, and into lead 9respectively.

The outer end of tubes I9 and 20 are open to permit the insertion of theglass tube 6 which contains the auxiliary electrodes 26, 21, and 28sealed in an atmosphere of air or other gases. The electrodes 21 and 28are suitably insulated from each other. The glass tube 6 should be ofquartz or other low dielectric loss glass in order to minimize loss ofreceived echo signal strength by keeping the leakage loss of receivedsignals across the cavity I il` between gapelectrodes I1 and I8 at aminimum.

In operation a direct current potential diiference, from leads 1 and-illrespectively, is maintained between auxiliary electrodes 21 and 28, thelatter being the cathode, causing a slow direct current discharge, andions resulting from the action of these so-called keep-alive electrodesdiffuse within the envelope to the region of the main gap I6. Shortlybefore the occurrence of the radio frequency transmitted pulse, a directcurrent pulse of relatively high amplitude is applied to electrode 26from lead 9, causing an intense direct current discharge to take placeacross the evacuated region within thev envelope 6 in the region of thegap I6 just preceding the occurrence of the high frequency transmittedtube 6 to -the parts, 53, 54, and 55,

pulse. The intense discharge Within the envelop constitutes a lowresistance path along which instant when the radio frequency pulsearrives.-

this direct current arc within the envelope', th; magnitude of the radiofrequency voltage for the' shorting arc is much smaller than Would/beth; case if the ionization and arc within the enve'e lope were notestablished in advance. The radi. frequency current which passesbetween'the elec, trodes I'I and I8 follows a course fromeach gap,electrode capacitively through the wall of glassI discharge arc within,then along this arc to a point opposite the othergap electrode and againcapacitively back through the,

Wall of glass tube 6 to the other I'hus although a short circuit betweengap electrodes frequency arc does not electrodes I1 and I8.

The electrodes 21 and 28, and also 2B are placed Well back from theregion of the main radio frequency gap I6 in order to prevent sputteringof gap electrode. is established I1 and I8. yet the radio actually touchthe gap the resonator and prolonging the useful life of the tube Sandauxiliary electrodes 26, 21, and 28. The outerv electrode 21 is extendedbeyond the center4 electrode 28 and is positive with' keep-alive orionizing electrode 40 is connected to one side of a positive directcurrent potential source through lead 4I, the other side of such sourcebeing connected through a ground connection, not shown, to theconducting cylindrical member 43 and thus indirectly to open endedconical member 49. The cylindrical member 43 encloses a resonant cavityhaving input and output coupling coaxial lines having conductors 45, 56,41. and 48.

Located opposite the conical member 49 is a second open ended conicalmember 50. These two conical members 49 and 50 constitute the radiofrequency electrodes between which the radio frequency short circuitingarc passes. A pre-firing electrode 5I is positioned'opposite electrode40 and is connected by lead 52 to a source providing periodically apulse of relatively high potential. A non-conducting envelope composedof'three permits reduction of pressure and use of other gases than airin the region of the radio frequency gap, and also gives support forauxiliary electrodes 40 and 5I. Ionization is caused by the potentialdifference existing between electrodes 40 and 49 and ions d iuse towardthe gap between the radio frequency electrodes t9 and 50. As describedwith respect to the structure Vof Figa-1 and 2shortly before theoccurrence of the transmitted radio frequency pulse a pre-firing pulseof relatively high magnitude'is impressed on electrode 5I by way of lead52 thus causing an intense discharge across the region of the gapbetween the radio frequency electrodes 49 and 50. This providesa lowresistance ionized path for'the radio frequency transmitted pulse to usein traversing the gap between electrodes 49 and 50, l

Fig. 4 is a half-sectional view' of the invention in an adaptation notemploying the pre-firing pulse but merely' establishing ionization inthe asesina 7 isolate a receiver from a common antenna during periods oftransmission and thereby to permit the effective use of one antenna forboth transmit- ,ting and receiving, comprising modulating means forproducing a series of timed trigger pulses, means for generating a pulseof relatively .high potential inresponse to each of said trigger pulses,means for delaying the trigger pulses, a, transmitter responsive to saiddelayed trigger pulses, an antenna, rst radio frequency transmissionmeans-.connecting said transmitter and said antenna, a, receiver,secondradio frequency trans mission means connecting said receiverI to a pointon said rst transmission means, a cavity resonator-containing a pair ofaxially aligned electrodes extending inwardly and forming a spark gaptherebetween and a nonconducting tube containing rareiled gases disposedwithin saidpair of electrodes and extending across said resonator, saidcavity resonator being connected between said receiver and the junctionof said two transmission means, said tube having auxiliary electrodesadapted to be maintained at a continuous potential difference, means forimpressing continuously on said auxiliary electrodes a potentialdifference for causing ionization, said tube also having an auxiliaryelectrode adapted to -be impressed with pulses of high potential forcausing ja breakdown are in theneighborhood of the gap at the time ofeach such pulse, and means conjnecting said means for generating highpotential 'pulses to said last-mentioned electrode. l

6. A system as in claim 5, said system further comprising an indicatorsynchronized with said delayed trigger pulse and connected to the outputof said receiver. 1. In 4a transmit-receive radio echo system, a sparkgap discharge switch having a prering electrode, a transmitter, meansfor generating trigger pulses. means for delaying said trigger pulses,means coupling said lundelayed trigger pulses to said preiiringelectrode and means coupling said delayed trigger pulses to saidtransmitter whereby said switch is energized `prior to the energizationof said transmitter.

8. In a transmit-receive radio echo system havling a transmitter, asingle antenna, a receiver,

,'iirst radio Vfrequency transmission means connecting said transmitterand 'said antennal and second radio frequency transmission lineconnecting said receiver to saidilrst transmission'means, a 'spark gapdischarge switch having' apr'efiring electrode connected between thereceiver and the 'fjiinctionoiV said two transmission means, means -forgenerating trigger-pulses, means forg delaying said triggerpulsesfmean's coupling said undelayed pulses to said-lA pre-ringelectrode', and mea-ns coupling said delayed trigger pulses to saidtransmitter whereby said switch is energized prior tothe energization ofsaid transmitter.

" 9; A shorting switch as in claim 3, said switch 'further comprising anauxiliary electrode dis- Aposed within the other of said hollowelectrodes in a region remote from said spark gap and within saidnonconducting envelope, and a pair oi metal tubes, teach of said tubesbeing supported concentric within one of said hollow electrodes .quencyenergy which comprises a pair of electrodes forming a spark gaptherebetween, a noliconducting envelope containing rarefied gasesdisposed within said pair ofelectrodes and extending across saidresonator, auxiliary ionizing electrodes disposed internally of one ofsaid pair of electrodes within said nonconducting. envelope and isolatedfrom said .pair of electrodes thereby, means for impressing on saidionizing electrodes a potential difference whereby a con," dition ofionization is produced in the regionfof said electrodes, an auxiliaryelectrode disposed within said envelope in spaced relationship to'saidionizing electrodes, and means for impressing pe?- riodically on saidauxiliary electrode a relatively high potential whereby an intensedischarge. is produced periodically within said nonconduc'ting envelopein the region of said spark gap, thereby providing a low impedance pathfor high frequency energy between said spark gap electrodes.

l1. In a, transmit-receive radiov ech'o system, combination ofa-resonant cavity having a line of maximum electric iield, a pair ofopen-ended ing adapted to be impressedwith-a constant. po'.-

tential diierence, means for producing said potential dierence, means:for applying said potential diierence to said plurality of electrodes,

lan auxiliary electrode disposed within said en.-

velope in spaced relation to said ionizing elec'- trodes and adapted tobe impressed periodically with a pulse of relatively high potential,means for producing said. pulse periodically, and means for applyingsaidpulse to ysaid auxiliary elec-.- trode, whereby an intense dischargel isproduced periodically within said nonconducting envelope to provide alow impedance discharge path for high frequency energy between saidopen-ended electrodes forming said spark gap. f j.

BRUCE B. CORKr- REFERENCES orrnp The following references are ofgreco'rdin lthe nie of this patent:

UNITED STATES PATENTS Date Number Name 1,986,397 Hund Jan. 1, 19352,106,770 Southworth -c Feb. 1, 1938 2,403,303 Richmond July 2, 19462,438,873 McCarthy Mar. 30, 1948 2,445,445 Marcum J-uly 20, 194,8l2,454,761 Barrow et al Nov. 30, 1948 2,459,152

Deisinger et al Jan. 18, 1949

